At 3:40, after he already came, she finally brings that free hand of hers up to his balls and gently strokes and caresses them while still tending to his dick. Notice his pleasurable reaction to both hands up there working on his cock and balls along with her mouth. Now, why didn't she do that in the moments leading up to his orgasm and all through it? Instead, like so many women in these blowjob videos, it is as if they've been forbidden to bring that free hand up to those balls and do something nice to them with it in order to make the whole experience that much better.